feat: add team invitation acceptance flow with email link routing

Implement end-to-end invitation acceptance: neutral entry route validates
token and routes to register (new users), login (existing users), or
auto-accepts (authenticated users). Handles 2FA token survival via
session, email case-insensitive matching, and dedicated error pages.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

resources/js/pages/auth/Login.vue

@@ -12,11 +12,21 @@ import { register } from '@/routes';
 import { store } from '@/routes/login';
 import { request } from '@/routes/password';
 
-defineProps<{
+type Props = {
     status?: string;
     canResetPassword: boolean;
     canRegister: boolean;
-}>();
+    invitation?: string;
+};
+
+const props = withDefaults(defineProps<Props>(), {
+    status: undefined,
+    invitation: undefined,
+});
+
+const registerUrl = props.invitation
+    ? `${register()}?invitation=${props.invitation}`
+    : register();
 </script>
 
 <template>
@@ -39,6 +49,8 @@ defineProps<{
             v-slot="{ errors, processing }"
             class="flex flex-col gap-6"
         >
+            <input v-if="invitation" type="hidden" name="invitation" :value="invitation" />
+
             <div class="grid gap-6">
                 <div class="grid gap-2">
                     <Label for="email">Email address</Label>
@@ -103,7 +115,7 @@ defineProps<{
                 v-if="canRegister"
             >
                 Don't have an account?
-                <TextLink :href="register()" :tabindex="5">Sign up</TextLink>
+                <TextLink :href="registerUrl" :tabindex="5">Sign up</TextLink>
             </div>
         </Form>
     </AuthBase>